If an exceptional incident occurs in a building, which can cause danger to the users of the building, it is important to enable a safe exit from the building for the users. This kind of serious exceptional incident can be e.g. a fire, an earthquake, a bomb threat or similar type of event, which is of danger to the people in the building. An evacuation order can be given to the building after detecting an exceptional incident, either for certain floors of the building or for the entire building. The transport systems located in the building, such as elevators, are in this case placed in an important role.
Generally all use of an elevator in the event of fire is separately prohibited. This is because a fire can seriously damage an elevator system, in which case elevators are no longer safe to use for evacuating people to the exit floor of the building. It is possible that the elevator stops working during an elevator run, in which case the elevator car may stop between floors leaving the elevator passengers trapped. In addition, a fire or smoke may spread strongly, especially along the elevator shaft, in which case the elevator is no longer a safe place owing to the oxygen supply or the heat. Also the extinguishing water used for extinguishing fires may damage the electrical parts of the system e.g. by causing short-circuits in the electronics parts of the system.
Additionally in the event of a fire it is not sensible to direct the elevator car and then open the doors to a floor on which the fire has progressed to an advanced stage. In this case the safety of the people already traveling in the elevator is endangered and the time needed for evacuation becomes longer, if it can be assumed that on this kind of floor there are no longer any people awaiting evacuation.
On the other hand, if the elevator system is constructed to be such that it withstands heat well or it is protected with suitable structures, the elevator system can very well be a feasible additional aid in the evacuation of the building. In tall buildings this is especially prominent, because the safe evacuation of a large number of people along the stairs and out of the building is extremely slow. If the elevators can be safely and reasonably controlled during an emergency, the evacuation time can be substantially shortened. It follows from the above that travel of the elevators in emergencies must be controlled in accordance with a special evacuation mode.
Publication U.S. Pat. No. 6,000,505 presents an appliance, with which a multiple level building can be evacuated during a fire incident using the elevator system. The appliance includes smoke detectors positioned on different floors. Elevator traffic is directed from the floors to be evacuated to the escape floor such that the doors of the elevator do not open on those floors on which a smoke detector detects smoke. The appliance also includes an emergency power source. The problem in the arrangement according to publication U.S. Pat. No. 6,000,505 is that the appliance is not able to forecast its own endurance and a consequence of this may be that the elevator could be performing an evacuation task at exactly the moment some critical component fails owing to e.g. strong heat in a fire incident.
Group control of elevators most typically means a way of managing the calls of an elevator system, in which the customer on the departure floor gives only direction information (up/down) to the call system. If several passengers arrive in the elevator lobby, who have the same direction of travel, the system does not know it before each of them has given information in the elevator car about his/her exact destination floor.
The so-called destination control of elevators means a destination call system, in which each elevator user gives his/her personal destination information to the elevator system in the elevator lobby before boarding the elevator car. This is implemented with a separate destination call panel in place of the up/down pushbuttons. In a destination system the giving of a separate call before entering the elevator car is not required and the stops of the elevators can be planned better than in conventional group control.
A problem with prior-art technology is that an effective evacuation mode in the event of an emergency has not previously been implemented for an elevator appliance included in a destination call system.